Structural wooden beams



J. c. JUREiT Y 3,399,833

STRUCTURAL WOODEN BEAMS Filed May 22, 1963 gli.

IIIII 805 78 l 82 r 80s INVENTOR.

w 4 g JOHN c. man l .Mi 45, 1; E v 1 l 4 f1 i 2 v HY 1 'i4- 85% L85 A TTORNEYS United States Patent O 3,309,833 STRUCTURAL WOODEN BEAMS John C. Jureit, Miami, F1a., assignor to Automated Building Components, Inc., Miami, Fla., a corporation of Florida Filed May 22, 1963, Ser. N 282,299 8 Claims. (Cl. 52-691) This invention relates to improved structural Wooden beams and more particularly relates to elongated wooden timbers which are uniquely reinforced to permit the timbers to support a load considerably in excess of that which could normally be borne by the timber itself.

In the ordinary use of elongated timbers for structural purposes, such as, for example, residential and industrial construction, the maximum load to which a timber beam of a given size may be subjected is determined by the characteristics of the lumber involved. Where a higher loading is necessary, it is conventional practice to merely increase the size of the timber until its cross section is adequate to bear the load las calculated by standard engineering procedures. In this manner, it is possible to provide adequate timbers for sustaining the structural loads in most applications.

However, while it is theoretically possible to always provide a large enough timber to carry whatever struc tur-al load is encountered, it frequently happens that the size of the timber which would be nee-ded in a particular environment is not suited to the available space. Also, it frequently happens that when adequate timber is provided for carrying the structural load at hand, the weight of the timber becomes objectionable. Of course, it would be possible to solve these problems by substituting metal for the timber but this frequently entails other disadvantages, such as possible increases in cost, diiculties in fabrication, or unsuitability to the particular finish desired.

According to the present invention, it has now been found that it is possible to provide structural timber members which are combined with metal in such a manner as to permit the timbers to carry a much greater load than would 'be indicated by the physical size of the timber alone. This construction permits the use of timber for structural purposes in environments where it would have been previously unsuitable and also permits the design of improved timbers for bearing structural loads which are tailor-made to the particul-ar structural unit involved. It is a feature of the invention that these unique timber members may -be formed in an economical fashion and that they may be provided in a size substantially no larger than the timber itself. According to cert-ain embodiments -of the invention, it is also possible to form elongated timbers from plural wooden members butted together in end-to-end fashion so that long spans may be provided without the necessity for unitary lengths of lumber. Another advantage which inures from the invention is the possibility of upgrading lumber to permit material savings in the cost of certain types of construction.

It is, accordingly, a primary object of the present invention to provide an improved composite structural wooden lbeam.

It is another object of the invention to provide an improved structural wooden beam formed of wood and metal in such a manner as to be able to sustain a load considerably in excess of that which could be borne by the Wood alone.

It is another object of the invention to provide an improved composite structural wooden member capable of bearing a structural load considerably in excess of that which could be borne |by the Wood alone and occupying considerably less space than the volume of wood which would be necessary to bear the same load.

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It is another object of the invention to provide an improved composite wooden structural member which may be manufactured in an economical fashion.

It is another object of the invention to provide an improved composite structural wooden member which is substantially no larger in size than the dimensions of the wood itself.

. It is Vanother object of the invention to provide an improved composite structural wooden beam formed from plural lengths of timber assembled together in butted fashion.

It is still another object of the invention to provide improved structural wooden beams combined with metal strips in a unique fashion to provide economical trussed beams.

These and further objects and advantages of the invention will 'become apparent upon reference to the following specication, claims and drawings wherein:

FIGURE l is a side elevation of a composite wooden structural member constructed according to one embodiment of the invention;

FIGURE 2 is a bottom view of the composite structural wooden member of FIGURE 1;

FIGURE 3 is an enlarged fragmentary depiction of one end of the metal reinforcing member utilized in the composite structural wooden member of FIGURES l and 2, the member being shown from the tooth side;

FIGURE 4 is `a side elevation of another embodiment of a composite structural wooden member formed according to the invention;

FIGURE 5 is a vertical elevation of an end of the composite structural member of FIGURE 4;

FIGURE 6 is a side elevation of a composite structural wooden member constructed according to another embodiment of the invention;

FIGURE 7 is a bottom view of the composite structural wooden member of FIGURE 6;

FIGURE 8 is a side elevation of another embodiment of composite structural wooden member formed according to the invention;

FIGURE 9 is a side elevation of a composite structural Wooden element constructured according to still another embodiment of the invention;

FIGURE 10 is a side elevation of a further embodiment of a structural wooden element formed according to the invention; and

FIGURE ll is a side elevation of still a further embodiment of a composite structural wooden element formed according to the invention.

Referring to FIGURES l and 2 there is seen a cornposite structural wooden beam which is indicated generally at 10 and which includes an elongated wooden member or timber 12. The member 12 is intended for iiexural loading from the top thereof and carries along its bottom edge 14 an elongated metal strip 16 which is fastened to the wooden member at its ends 18. 'I'.he center 20 of the strip 16 is spaced from the bottom edge 14 of the wooden member 12, as by means of a wooden block 22, so that the wooden member and metal strip form a trussed beam. Referring to FIGURES 2 and 3, the ends 18 of the metal strip 16 have struck therefrom slender elongated nail-like teeth which are imbedded in the lower edge of the wooden member 12. If desired, similar teeth may be provided for holding the -wooden block 22 in position. Alternatively, teeth may be provided along t-he entire length of the metal strip 16.

According to the invention, the teeth which are struck from the ends 18 of the metal strip 16 are of such a nature as to not lonly withstand the shear load to which they are subjected by flexural loading of the beam 10, but also to provide withdrawal resistance and thereby in and of themselves hold the metal strip 16 in position on a the wooden member 12. In order to provide adequate withdrawal resistance without undue destruction of wood ber, it has been found that the teeth must be slender, elongated, and nail-like in character, so as to act as true nails in the manner of the teeth described in United States Patent No. 2,877,520. When the teeth are formed in this manner, the entire, composite, structural beam may be formed by merely pressing the teeth on the strip 16 into the ends of the wooden member 12. In a similar manner, the teeth in the center of the strip 16 may be pressed into the block 22, where such center teeth are provided, it being recognized that such teeth may not be necessary in sorne installations.

Referring to FIGURE 3, there is shown a specific embodiment of an end 18 of the strip 16 containing a plurality of rows of teeth of 24-36, it being understood that the crosses indicated at 38 at the right hand side of the end 1S indicate the positions of additional teeth struck in the same pattern as the illustrated teeth. It will be noted that each row of teeth leaves a corresponding ro'w of slots in the metal plate from which the teeth were struck. Alternate rows of teeth, such as rows 24 and 26, are preferably struck in opposite directions and the teeth in alternate rows are preferably staggered in a transverse direction.

According to a specific embodiment of the invention, the metal strip 16 may be formed of l4-gauge mild steel galvanized plate `having a nominal thickness of 0.075 inch. The distance A between teeth in the same row may be 1'5/16 inches, the distance B between teeth in adjacent rows along the length of the plate may be 21/32 inch and the length of the teeth, that is, the distance that they extend away from the plate, may be 1%6 inch. The width of the teeth C may be ls inch and the distance D between adjacent rows of teeth may be :Vs inch. When utilizing the metal strip with the more common structural lumbers, such as r and yellow pine, the length of the teeth should be maintained within the limits of approximately six to seventeen times the thickness Vof the plate.

In a specific embodiment yutilizing a 2 X 8 piece of fir, sixteen feet long, the width of the mild steel strip 16 may be the same as the -width of the 2 x 8, the thickness of the strip may be nominally 0.075 inch, and the length of the attaching ends 18 may be 12 inches. The block 22 may space the center 20 of the strip 16 from the lower edge of the wooden beam 12 by a distance `of siX inches, all of the foregoing being given by way of specific example and not intended in a limiting fashion.

Referring to FIGURES 4 and 5, there is shown another embodiment of a composite structural wooden beam comprising an elongated timber 40 reinforced by an elongated metal strap 42. In this embodiment of the invention, the ends 44 of the metal strap 42 are provided with teeth 46 of the type described in conjunction with the embodiment of the invention of FIGURES 1 3, and these are embedded in the end faces 46 of the timber. In this particular embodiment of the invention, three spacing blocks 48 space the central section 50 of the strip 42 from the lower edge 52 of the timber 40. In the illustrated form, the strip 42 is the same width as the timber 40, athough the strip need not necessarily be this wide in either this embodiment lor the embodiment of FIG- URES 1-3.

Referring to FIGURES 6 and 7, there is shown still another embodiment of the invention wherein an elongated timber 54 has aixed to its lower surface 56 an elongated metal strip 58. As is seen in FIGURE 7, the strip 58 has at its ends 60 a plurality of teeth of the type discussed in conjunction with the embodiment of the invention `of FIGURES 1-3 which are embedded in the f imber 54. While these teeth are shown only at the ends of the metal strip 58, it is also possible to provide the teeth throughout the length of the strip and this permits the manufacture of various lengths and sizes of composite structural timbers Without the necessity of maintaining a large inventory of different types of metal strips. That is to say, when the metal strips are provided with teeth only at the ends, as in the embodiments of FIGURES 2, 5 and 7, it is necessary to maintain an inventory of strips of different lengths corresponding to the different lengths of timbers which it is desired to manufacture. On the other hand, where the `metal strips are provided with teeth throughout their length, a composite timber of any length may be prepared by merely cutting the metal strip to the desired length and then aflixing it to the wood in any of the manners disclosed herein. While the number of rows of teeth in any given strip may vary within the purview of the invention, it is desirable to have at least two rows, or to have at least transversely spaced teeth, so that the strip is self-supporting on its teeth when the lumber is in an inverted position to permit automated pressing of the teeth into the lumber.

Referring to FIGURE 8, there is shown still a further embodiment of the invention wherein an elongated wooden timber 62 is reinforced by a pair of elongated metal strips 64, one on either side thereof (only one strip being visible `in FIGURE 8), the strips being positioned adjacent the lower edge 66 of the timber 62. The ends 68 of the strip 64 are provided with teeth in the manner described in the embodiment of the invention of FIG- URES 1-3, it again being apparent that the strip 64 may be provided with teeth over its entire length, if desired.

Referring to FIGURE 9, there is shown still another embodiment of the invention wherein the elongated timber shown generally at 70 is formed of a pair of timbers 72 and 74 joined -by connector plates 76 of the type disclosed in United States Patent No. 2,877,520. The elongated timber 70 is reinforced by an elongated metal strip 78 having ends 80 provided with teeth of the type discussed in det-ail in conjunction with the embodiment of the invention of FIGURES 1-3, these teeth being embedded in the timber 70. The center 82 `of the strip 78 may be spaced from the lower edge 84 of the timber 70 as by means of a block 86. Alternatively, it is possible to form an elongated timber of butted wooden members with the metal strip 78 in engagement with the lower surface l84 along its entire length, as is illustrated in FIG- URE l0, similar reference numerals being used throughout.

Referring to FIGURE 11, there is shown still another embodiment of the invention wherein an elongated tim- =ber 82 is reinforced with a pair of metal strips 84 on opposite sides of the lower surfaces thereof as in the embodiment of the invention of FIGURE 8. However, in the embodiment of FIGURE l1, the metal strip 84 is provided with teeth along its entire length, but the spacing of these teeth is closer at the ends 86 than at the center 88. That is to say, the distance E1 is smaller than the distance E2 in order to provide a greater number of teeth per unit area at the ends of the beam than at the center. It is found that this arrangement provides an even distribution of load and diminishes the load borne by the teeth in the ends 86 without at the same time cutting unneccessary wood fiber, as may be the case where the density of the teeth is uniform throughout the length of the beam.

In all of the embodiments illustrated in the drawings, the metal strips are provided on the side `of the beam which will normally be subjected to tensile stress under the beam loading which is contemplated. Generally speaking, beams to be loaded in tiexure are normally loaded from only one surface and this is the top surface yin the embodiments of the invention illustrated in the drawings. It will be apparent to those skilled in the art that where the beam may be subject to flexural loading in two directions, metal strips may be provided along both edges of the beam rather than the single edge shown.

It will be apparent from the foregoing that when beams are constructed according to the present invention they may be formed from conventionally utilized lumber, such as tir or yellow pine, and may be made to carry structural loads considerably in excess of those which could be carried by lumber of similar dimensions. In most ernbodiments of the invention the composite beam occupies substantially no more space than the lumber itself so that 5 prohibitively increase the cost of the structural element. l0

Fabrication lof the composite beams may be extremely simple in character, necessitating only an embedding of the teeth in the metal strip into the timber. Where the metal strip is provided with teeth along its entire length,

it is feasible to provide `the strip with the teeth in coils or in relatively long lengths Awhich may then be cut to order in the formation of composite beams. The entire larrangement permits low cost fabrication and low cost construction, in that lower cost lumber may be utilized for structural jobs which would otherwise have to be performed by higher priced lumber or metal. While the teeth are described as slender, elongated and nail-like, it will be 'apparent to those skilled in the art that the sides `of the teeth maybe barbed, the bases of the teeth may be widened, as with the heads of nails, and the teeth may be V-grooved in cross section, all while retaining their slender, elongated and nail-like shapes.

The invention may be embodided in other yspecific 'forms without departing from the spirit or essential characteristics thereof. The present embodiments 'are there- 30 fore to be -considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims lare therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. A structural wooden beam comprising an elongatedwooden member adapted to be subjected to transverse loads so as to cause tensile stresses on one side of its neutral surface and an elongated metal strip extending along a surface of said beam subject to said tensile stress, said metal strip extending along at least the major portion of the entire longitudinal length of said surface subject to said tensile stress and attached thereto solely by means of a plurality of slender elongated nail-like teeth struck from said strip and pressed into said wooden member,

there being at least a group of said teeth disposed adjacent each end of said strip, said teeth having a length `adequate to provide `withdrawal resistance which maintain said strip in position on said wooden beam.

2. A structural wooden beam as set out in claim wherein said strip is mounted on a surface of said Wooden member which is substantially perpendicular to the direction of said transverse load.

3. A structural wooden beam =as set. out in claim 1 wherein said strip is mounted on a surface of said wooden member which is substantially parallel to the direction of said transverse load.

4. A structural wooden beam comprising an elongated member adapted to be subjected to transverse loads so as to cause tensile stresses on one side of its neutral surface, and an elongated metal strip extending along a surface of said beam subject to said tensile stress, said metal strip extending along the entire longitudinal length of said surface subject to said tensile stress and having bent over ends extending substantially perpendicular to said surface subject to said tensile stress, said ends having slender elongated nail-like teeth struck therefrom and embedded in ends of said wooden member, said teeth extending generally parallel to the longitudinal axis of said beam, said strip being secured to said beam solely by said teeth.

5. A structural wooden beam comprising an elongated wooden member adapted to be subject to transverse loads so as to cause tensile stresses on one side of its neutral surface, and a pair of parallel elongated metal strips extending along opposed surfaces of said beam which are subject to said tensile stress, said strips extending along at least major portions of the entire longitudinal length of said beam and attached thereto solely by means of slender elongated nail-like teeth struck from said strips and pressed into said wooden member, there being at least a group of said teeth disposed adjacent each end of said strip, said teeth having a length capable of providing the necessary withdrawal resistance to maintain said strips in position. v

6. A structural wooden beam as set out in claim 1 wherein said teeth are provided only in groups at the ends of said strip.

7. A structural wooden beam as set out in claim 1 wherein said teeth are provided along substantially the entire length of said strip.

8. A structural wooden beam as set out in claim 1 wherein the number of teeth per unit area of said strip is greater near the ends of said strip than at portions intermediate the ends.

References Cited by the Examiner UNITED STATES PATENTS 133,306 ll/l872 Cutler 52-727 2,601,910 7/1952 Nichols 52-727 2,813,310 11/1957 Harrison 52--131 X 2,877,520 3/ 1959 Jureit 287-2092 3,068,738 12/ 1962 Nulick 27.87-20.92 X

FOREIGN PATENTS 859,522 12/1952 Germany.

348,366 5/1931 Great Britain.

RCHARD W. COOKE, IR., Primary Examiner.

JACOB L. NACKENOFF, FRANK L. ABBOTT,

Examiners.

K. E. PAYNE, L. R. RADANOVIC,

Assistant Examiners. 

1. A STRUCTURAL WOODEN BEAM COMPRISING AN ELONGATED WOODEN MEMBER ADAPTED TO BE SUBJECTED TO TRANSVERSE LOADS SO AS TO CAUSE TENSILE STRESSES ON ONE SIDE OF ITS NEUTRAL SURFACE AND AN ELONGATED METAL STRIP EXTENDING ALONG A SURFACE OF SAID BEAM SUBJECT TO SAID TENSILE STRESS, SAID METAL STRIP EXTENDING ALONG AT LEAST THE MAJOR PORTION OF THE ENTIRE LONGITUDINAL LENGTH OF SAID SURFACE SUBJECT TO SAID TENSILE STRESS AND ATTACHED THERETO SOLELY BY MEANS OF A PLURALITY OF SLENDER ELONGATED NAIL-LIKE TEETH STRUCK FROM SAID STRIP AND PRESSED INTO SAID WOODEN MEMBER, THERE BEING AT LEAST A GROUP OF SAID TEETH DISPOSED ADJACENT EACH END OF SAID STRIP, SAID TEETH HAVING A LENGTH ADEQUATE TO PROVIDE WITHDRAWAL RESISTANCE WHICH MAINTAIN SAID STRIP IN POSITION ON SAID WOODEN BEAM. 